I recently installed an original Bosch fog lamps in my 240 with an original rockjer switch. I would like to know if I wired it correctly, upon switching "ON" of the park lights, the rocker switch pilot bulb also lights up color "GREEN". Is this normal? I was expecting the rocker switch to light up only upon switching "ON" the fog lamps. Some other rocker switches with built in pilot lamps emit a dull light and brightens up upon switching to "ON". Did I do something wrong with the connections?

Short answer, I hope:

The switch has three terminals.

First terminal is connected to whatever source of power you choose. Park lights, low beams, etc.,

Second terminal is connected to the fog lights. It is hot only when the switch is ON. Inside the switch is a connection from this to one side of the indicator lamp.

Third terminal is connected to a newrby ground. This provides the ground side for the indicator lamp, nothing else.

If you aren't sure which terminal is which, do a test to be certain. I have one Volvo Wirin Diagram picture that shows the terminals to be marked "+" (from the power source, "S" (to the lights) and "31" the ground connection.

They may or may not be accurate for what you have.


The sugestion from Ken C of a relay in the circuit is an excellent idea.

Without one the additional load on the wiring you tap into for the power source will be heavy and might cause an overheating problem. Use any of the "cube" type ones, either a 4-prong or a 5-prong will work. You will need both a relay and the base, and if you get them from a junkyard, cut the leads long.

Post back if you want some directions on connecting a relay into the system.

Good Luck,

Bob

:>)

Have one of those from a PUP trip wired in.

Get a generic relay from Radio Shack or the local auto store. You need a 30 or 40 amp single pole/double throw relay. They are less than $5, and get a sealed fuse holder and a fuse rated for your lights wattage. You can hook up to the relay using spade lugs or you can purchase a connector.

I used switched power from the fuse box as the power source. You can run the lights without headlights and they go off when you turn off the key. That is how the rear ones work, of course they are not switched by a relay. That is a straight 12 volts to the bulbs.

Run the power to one side of the switch. On the other pole connect it to the relay (I have mine under the hood) and to one side of the light bulb. Run the other side of the bulb holder to the ground in the center of the dash. On the relay hook the wire from the same side of the switch as the bulb to coil + and hook coil - up to someplace like the headlight ground. Then you run a 18 gauge wire from the battery plus through the fuse holder to your relay contact. Run the other side of the relay to your bulbs per the wiring diagram and you are good to go.

The light does not come on until you flip the switch, and stays off until you flip it. A slight glow of the bulb should not be there with the switch off. That would mean you have a current flow from somewhere and you do not want that.

Regards,

Paul

Just sounds like you mixed up the switch's connections -- if they aren't plainly marked, I always like to confirm the internal circuit with a VOM set on ohms, just to make sure I understand the circuit.

It's been a while, but from a vague memory, there should have been three contacts in back of the switch. One should be +, your 12-v supply; another should be "S", the output to the *RELAY* for the lights (assuming you are wisely using a relay to ensure adequate voltage to the lamps); and the third, coming out of the bulb holder, is for the bulb's ground.

Hi Ken

I'll check on the connections this weekend and use your reply as guide. With the park lights on, what is visible on the fog lamp switch while on "OFF" and "ON" position?

re: "...With the park lights on, what is visible on the fog lamp switch while on "OFF" and "ON" position?..."

The way I would wire the switch (i.e., with the three terminals, as I described them from memory in my first message), nothing should be lit when the parking lights aren't switched on.
That's assuming that you're tapping the parking lights as the 12v source of power into the switch (i.e., to the + terminal).
That way, the fog lights won't turn on unless the parking lights are also on (i.e., the light switch must be turned to either "parking" or "head" lights).

Then, if the switch is turned on (with parking lights lit), power is conducted through it to the output (terminal S), as well as through the tiny bulb inside the switch and on to its ground.

There's nothing that would light the bulb if the parking lights weren't on. But when the parking lights are lit, there could be something inside the switch (e.g., a resistor and diode) that could light the bulb dimly if the switch is "off", and light the bulb brightly if the switch is "on". That would be an easy internal circuit.
But honestly, it's been so long since I used this switch in a car (i.e., I haven't owned that car in over 10 years) that I honestly don't remember if the switch had that feature or not. Perhaps someone else could comment on this point.

In any case, it's plain that if you're using the parking lights as your initial 12v input into the switch, if the switch feeds directly to the fog lights you would be putting a heavy additional load on the parking lights' circuitry (wire, fuses, and even the light switch). A relay would substantially ease that burden.

And don't forget that many people wire their fog lights so (and, in fact, in certain european countries it is required) that the fog lights cannot work with the high beam headlights -- i.e., they should only work with the low beams rather than the parking lights:
(1) if it's foggy, you may (in your state) be required by law to use your (low beam) headlights;
(2) you shouldn't be driving around all the time with your fog lights on (as many idiots do), as it can bother other drivers -- if you want DRLs, instead, they should be of a lower intensity, such as 25w incandescents, or LEDs (like I did, see below) so they're noticeable, but not annoying;
(3) and fog lights are not driving lights (although, again, many idiots in this country aim them as if they are), so they shouldn't be used with the high beams.
Therefore, you might want to tap the low beam headlights' circuit for the 12v input power to the switch, instead of taking it from the parking lights.

I'm not criticizing what you're doing (I'm only criticizing the aforementioned idiots who drive around all day long with the fog lights on and aimed high to blaze in other drivers' eyes), so please don't take it as such -- just offering suggestions :-).

Good luck.

1. The rocker switch does not light up when the park lights are "OFF".
2. I did not use a relay, (one of my mistakes)in the connection.
3. Fog lamps can only be used when the park lights are "ON". (another mistake, the connection should have been tapped on the low beam light.)
4. When park lights are "ON", rocker switch lights up, same brightness when the fog lamps are turned "ON". There is no difference in brightness whether ON or OFF. ( I sure hope you are right that there MIGHT be a dull light on the switch when the park lights are turned ON while the rocker switch is in "OFF" position.b

I will rectify the connections this weekend and update you after.

re: "...When park lights are "ON", rocker switch lights up, same brightness when the fog lamps are turned "ON". There is no difference in brightness whether ON or OFF...."

Okay, here's my theory. I think you have the current going through the switch in reverse of the path that was intended. See if you agree....

The switch was intended for current to enter the + terminal (on top, opposite the lamp's ground terminal):
When off, the switch's open contacts would stop the current at that point -- it would go no farther.
But when on, the switch's closed contacts would allow the current to flow farther, through the internal circuit where it branches both to the S terminal (that's in the middle) as well as to the bulb, where it would flow through the bulb and on to it's ground (the terminal coming out of the bulb holder). In other words, the S (output) terminal and the bulb are always connected, whether the switch is open or closed.

But I think you wired the + and S terminals in reverse! Power is going in to the S terminal (where it is internally linked to the bulb), keeping the bulb lit all the time (as long as the parking lights are on). In this condition, the switch still interupts the power outward, through the + terminal, but the little bulb isn't affected.

Reverse the + and S connections and I think it will work correctly.

Good luck.

seems logical. I'll check on it. thanks.

I think the switch is just a simple open/ closed circuit. As long as you tap the + for the light bulb on the same side as the load to the fog lights.